A LITTLE WORD KNOW-HOW
Cryptogram Strategy: Short Words and Repeated Patterns
Decode a substitution puzzle by testing patterns across the whole sentence.
Use structure first
Spaces and punctuation survive in our cryptograms. Notice repeated words, one-letter words and doubled letters. They are clues about structure before you know any particular letter.
Test a hypothesis in several places
If a three-letter word might be THE, apply the proposed mapping to the rest of the text. The same cipher letter must mean the same decoded letter everywhere. A guess that helps one word but damages several others deserves another look.
Keep a reversible approach
Replace uncertain mappings rather than building an elaborate theory around them. In our game each decoded letter belongs to one cipher letter. A conflicting reuse is a signal to revise a guess, not a rule exception.